1. Field of the Invention
The present invention relates to valves used to control the flow of fluids within a conduit and, more particularly, to a combination ball and check valve.
2. Description of Related Art
Ball valves are used to alternately permit and prevent fluid flow through a conduit. Likewise, one-way or check valves are used to permit fluid flow therepast in a first direction and to prevent fluid flow therepast in a second direction. In many industrial applications valve seats within a ball valve and within a check valve must be serviced to prevent fluid leaks. A problem with this arrangement is that when the valve closure member of the check valve is to be serviced, all of the fluid and pressure within the conduit on both sides of the check valve must be drained. In conduits of much length between the valves, the need to drain all of the fluids and pressure on both sides of the check valve can be time consuming and costly, especially in petroleum refining operations. Additionally, when ball valves are to be serviced there is the same need to drain all of the fluid and pressure within the conduit on both sides of the valve to be serviced.
In the past both ball and check valves have been used adjacent one another, but there is the need for a valve that does not require the removal of the fluids and pressure within the conduit on both sides of the valve to be serviced. Also, there is a need for a valve that has redundant fluid closure features within a packaging that permits weight, space and cost savings over conventional single valves.